120 FUNGUS DISEASES OF MAN AND ANIMALS 



the rusts, smuts, mildews, and leaf spots can be mentioned as familiar 

 examples. Comparatively few plant diseases are caused by bacteria. 

 Among the diseases of man and animals, on the other hand, bacterial 

 diseases predominate, and the list of important fungus diseases is 

 short. Furthermore, at least in the case of most of the generalized 

 and frequently fatal mycoses, the fungus appears to be an accidental 

 invader and does not spread from man to man. Fungi therefore ap- 

 pear to be poorly adapted to a parasitic existence in man except in 

 a few instances. 



Importance of Mycoses. Although fatal fungus diseases in man 

 are less common than bacterial infections they are nevertheless nu- 

 merically important. In Vital Statistics of the United States for 

 1942 mycoses are reported as causing 359 of 1,385,187 deaths in man. 

 This is less than 0.03 per cent of the total, yet it is more than half 

 the number of deaths caused by either typhoid, tetanus, or polio- 

 myelitis and polioencephalitis; more than the number of deaths due 

 to Rocky Mountain spotted fever and the other typhus-like diseases 

 together ; and nearly twice as many as the sum of all those caused by 

 paratyphoid fever, undulant fever, smallpox, rabies, leprosy, plague, 

 cholera, yellow fever, and relapsing fever. It should be pointed out, 

 of course, that the low mortality rates of some of the well-known 

 diseases just mentioned are due to the enforcement of effective con- 

 trol measures, whereas in the case of the generalized mycoses control 

 measures are not practiced nor, indeed, are they known. Non-fatal 

 mycoses such as the dermatophytoses (ringworm, athlete's foot) are 

 perhaps as common as any bacterial disease. 



Besides their numerical importance, as compared with some of 

 the better known bacterial diseases, the fungus infections provide 

 useful material for the study of certain biological principles. For 

 example, the phenomena of variability and mutation are more ap- 

 parent in the fungi and can be studied with greater confidence be- 

 cause the larger size and the abundance of measurable morphological 

 characteristics of fungi make it easier to distinguish between a true 

 mutant and a contaminant. 



Types of Mycoses. Fungus infections are referred to as mycoses, 

 frequently with a prefix or qualifying word to indicate the part 

 affected, as otomycosis (ear), onychomycosis (nail), pulmonary my- 

 cosis. More frequently the type of mycosis is designated according 

 to the etiological agent, as actinomycosis, blastomycosis, coccidioido- 

 mycosis. In any case it is usually necessary to indicate the specific 

 fungus responsible since different fungi may invade the ear or the 

 lungs, and different species of actinomycetes {Actinomyces bovis, 



